1. Field of the Disclosure
This disclosure relates generally to apparatus and method for completing wellbores that utilize one or more shape conformable devices or members containing shape memory alloys, including, but not limited to, packers, sand screens, seals and inflow control devices.
2. Background of the Art
Wellbores are drilled in subsurface formations for the production of hydrocarbons (oil and gas). Wells often extend to depths of more than 15,000 feet and have downhole temperatures exceeding 300° F. After a wellbore is formed, a production string is installed therein for efficient production of the hydrocarbons from subsurface formations. The production string may be installed in an open hole or a cased hole and typically includes a tubing that extends from the surface to the wellbore depth. A variety of devices are placed inside and around the tubing for efficient production of hydrocarbons from the subsurface formations. Some of these devices may utilize materials or members that expand when heated. Such materials are generally referred to herein as “conformable materials” “shape memory materials”, or “swellable materials” and the devices that utilize such materials as “conformable devices.” Such devices are installed on the production string in their unexpanded or compressed state or form and expanded to their expandable state by heating such devices in the wellbore. Conformable devices include, but are not limited to, packers, sand screens, seals and certain flow control devices. Shape memory materials or swellable materials that contain non-metallic materials, such as polymers, have been utilized for making shape conformable devices and members. A polymer shape memory material has a glass transition temperature and when such a material is heated to or above such temperature, it expands. The expanded material is then compressed at this elevated temperature to a desired compressed shape for use in a wellbore while the temperature is at or above its glass transition temperature. The compressed shape memory material retains its shape when its temperature is reduced below the glass transition temperature. When reheated to or above its glass transition temperature, the member expands to its original expanded shape and retains the original expanded until compressed at or above the glass transition temperature.
To form a member from a polymer shape memory material, the material is heated from an ambient temperature to a temperature at or above its glass transition temperature and shaped or formed into a neutral shape or desired expanded shape. The neutral shape is the desired shape after deployment of such member at a suitable location, such as in a wellbore. It is then compressed at a temperature at or above its glass transition temperature to a compressed shape or an intermediate shape and then cooled to a temperature below the transition temperature to cause the shape memory member to retain the intermediate shape. The intermediate shape is the desired shape suitable for running the device into a wellbore. The device is then placed in the wellbore and, heated in the wellbore to or above the glass transition temperature to cause it to expand, thus deploying it in the wellbore. Such a process is relatively cumbersome and requires controlled heat chambers and facilities to mold the polymers at high temperatures to their intermediate or compressed shapes. In addition, polymer shape memory materials have lower operating temperatures and lower mechanical strength compared to alloys. Furthermore, polymer shape memory materials have low thermal conductivity and thus require a relatively long time to expand to their neutral or expanded shape after they are heated.
The disclosure herein provides shape conforming devices that contain one or more shape memory alloys and methods of deployment of such devices.